What companions can you marry?

I had an interesting idea suddenly of a husband and wife taversing through the wild unknowns of Skyrim, digging into dungeons. Nord and Nord at each other's side. Her an illusionist and him a strapping swordsman or something.

I think there is a list of them all on the Wiki or UESP.

Aela, Farkas, Vilkas, Athis, Njada, Ria, and Torvar

Those being companions from the Companions.

For follower companions you can marry, the full list of eligible NPCs http://www.uesp.net/wiki/Skyrim:Marriage#NPCs_available_to_be_married. The grid will tell you whether or not each NPC is a follower.

I think she's going to marry Stenvar.